As society began to develop and build the infrastructure of this country, rights-of-way for roads had to be established. Then with the advent of electricity and other utilities, rights-of-way for power and telephone lines, and water, gas and oil pipelines, and the like, became necessary. Once a right-of-way is established, continuous maintenance is required. In the early days all maintenance was done by hand. As time passed, machinery, tools and equipment have been developed to fill the needs and requirements for right-of-way maintenance work.
In right-of-way maintenance, mowing is an expensive and labor intensive operation. The reason for this is that typically the area covered by the right-of-way was once forest. Trees and brush continually regrow after they are mowed. As a result, the right-of-way must be mowed every three to five years (this is referred to as the mowing cycle) in order to facilitate entrance, access, etc., to utility and roadside rights-of-way, forested areas, and anywhere brush, trees, grass, or other vegetation are considered to be a nuisance or are unwanted. Therefore, there is a very serious need to extend the mowing cycle in order to save save money and labor and to keep the rights-of-way in better condition, which will reduce the amount of wear and tear on other maintenance equipment.
For many years the industry has been using herbicides in an effort to extend the mowing cycle. Many different types of equipment and methods have been devised to apply chemicals in the right-of-way. However, with each new device or application method comes a new set of problems, many of which have yet to be solved. An early attempt to apply herbicides was with conventional agricultural sprayers. Other than structural failure, which could be solved with a redesign, the greatest problem was wind drift of the herbicide. When this happened the chemical would drift into the adjacent forest or private property adjoining the right-of-way and kill the trees in the forest or on the private property. This resulted in many law suits and cost the utility companies millions of dollars.
Presently the "Radial Arc Sprayer" is the most common method of applying herbicide to the right-of-way. A disadvantage of this apparatus is that the trees and brush must be allowed to regrow to about four feet tall before application of the herbicide. This leaves the right-of-way covered in a blanket of brown vegetation that is not only unappealing but is also detrimental to the environment. Since the vegetation never drops the dead leaves and the regrowth is much more dense than natural growth, the ground below is so shaded from sun light that grasses, flowering plants and seed bearing plants cannot grow. Without these plants, small animals, birds, etc. have no food source in the right-of-way. Therefore, no ecosystem can form there. In addition, since the chemical is held in the four feet of regrowth it cannot be mowed. If mowing is done at this point, only the portion of the growth to which the chemicals have been applied will be cut. As a result, the trees and brush bud out and grow again just as if they were never treated. Having this standing vegetation in the right-of-way makes other maintenance difficult and is detrimental to other maintenance equipment.
The condition most favorable for the utility company, aesthetic appeal and the environment is for the right-of-way to be mowed reasonably close to the ground and the vegetation to be treated in a manner that does not allow rapid regrowth. Early attempts at achieving this condition consisted of mowing the right-of-way, then following up soon with a soil activated herbicide. This procedure worked, as far as the condition of the right-of-way. However, the roots from trees and plants in the adjacent forest and in the lawns of adjacent residences typically extend into the right-of-way. Thus, these trees and plants are also killed by the soil activated chemicals. Again law suits have been filed and millions of dollars spent by the utility companies to settle these suits.
Devices have been developed that will mow the vegetation and apply herbicide under the mower deck directly to the stems. The herbicides used by these devices are "soil deactivated", which solves the problem of killing adjacent vegetation. Since the herbicide is applied under the deck, the problem of wind drift has been solved. There are generally two different designs of these machines. One drops a tiny stream of chemical onto the blade carrier of the mower, using the centrifugal force it creates to atomize and spread the chemical across the width of the mower. The other device pumps the chemical through the gearbox shaft and blade carrier and out an orifice associated with the mower blade. The rotation of the mower blade causes the chemical to be dispersed radially as it exits the orifice. This is intended to innoculate the end of the stem as it is being cut.
The problem with these devices is that herbicide is applied to all of the biomass, debris, etc. that passes through the mower. Since the herbicide used is "soil deactivated", only the chemical applied directly to the stem is of any effect while the remainder is destroyed by the soil. The small amount of chemical applied to the stem is not enough to give effective control. To alleviate this problem would require applying such a large amount of chemical as to be cost prohibitive. Also, that amount of chemical is outside label allowance and is prohibited by law.
What is needed is an apparatus and method for delivering an effective and legal predetermined or job specific amount of pesticide/herbicide directly to the stem of the nuisance vegetation with minimal waste.